The phrase "keep purchasing" is correct and usable in written English.
It means to keep buying something. For example, "If you want to keep up with the latest trends, you should keep purchasing new clothes every season."
"They complained for a day or two, but keep purchasing the same as always".
Improved relations between the United States and the Soviet Union have resulted in a series of arms reductions, and lawmakers are showing an increasing reluctance to keep purchasing new military hardware.
Fed officials decided Wednesday, at the conclusion of their first policy meeting of 2013, to keep purchasing $85 billion a month of mortgage-backed and Treasury securities and signaled no intention, for now, to let up". Jon Hilsenrath and Victoria McGrane in The Wall Street Journal.
Given that COLAs are designed merely to keep purchasing power constant, this is a large gain.
Glucose testing machines can be had for free, but you'll need to keep purchasing the aforementioned testing strips forever.
One might argue that real world mangers of large processing firms like Isfahan Steel Company keep purchasing from different sources to ensure a continuous and reliable stream of supplies.
Keep purchased, stratified seeds in the refrigerator in a plastic bag.
When the Swiss National Bank (SNB) abandoned its exchange-rate peg last month, causing the franc to soar by a nosebleed-inducing 20%, it seemed to be acting out of fear that it would suffer balance-sheet losses if it kept purchasing euros and other foreign currencies.
Volume buying keeps purchasing cost low.
"[It has made] London the most sought-after city for the super-rich". Buying via an offshore company allows purchasers to avoid stamp duty and makes it easier to keep purchases private.
I soon give in to the call of consumerism, but keep purchases small – not the latest micro-camera, but what I'll call "cuteware".
