The phrase "although not free" is correct and usable in written English.
It can be used to indicate a condition or limitation, often in contrast to something that is free or unrestricted.
Example: "The service is available to all users, although not free, it offers premium features that enhance the experience."
Alternatives: "even though it comes at a cost" or "despite not being complimentary."
"I have been out of prison, although not free, for one year.
With the memories of the protests, violence, and deaths that followed the 2005 general elections still fresh in the minds of many Ethiopians, the political climate prior to the 2010 elections was somewhat subdued, although not free of controversy.
For users Mint is quite literally free, although not free of conflicts of interest.
Although not free money, small business loans can sometimes be preferable to giving up more equity in the short term.
Albeit citations may be made with a variety of purposes, it is a common practice, although not free from known criticisms (e.g., Bornmann and Daniel 2008), the use of citation data to assess a scholar's impact on a given discipline or field (Culnan 1987; Tahai and Meyer 1999).
Although not free from interpretation, qualitative description attempts to make as few inferences as possible during data analysis [ 28, 29].
Although still not free to leave Sudan, Ms. Ibrahim has, at least for now, been reunited with her husband and the child she delivered while in prison.
Doctors and patients say the new drugs can offer some men a decent quality of life, although they are not free of side effects.
Such help, although voluntary, is not free.
Although Hindus are not free from homophobia, the Hindu tradition offers teachings that enable Hindus and Hindu leaders to offer unconditional love and support for LGBT people.
These high-throughput techniques have been shown to be highly informative, although they are not free of errors and biases either [13].
