Yes, you can activate and deactivate as often as you like, the activation is easy as you can do that online, deactivating is more difficult in the sense you have to call and request it. One thing to note, when you activate it, be sure to chose the monthly service plan that doesn't commit you to a year service as once you have completed the first 30 days there is no way out other than to pay the ETF, it will cost more to go month to to month typically. There might be an exception if the Tivo has been active on your account in the past or has a grandfathered lower rate in its TSN history.
When you call to cancel, they may give you the third degree of "why would you want to cancel?" and might as mentioned offer you the $99 lifetime upgrade fee if the Premiere has been active for long enough, long enough meaning the total time that Premiere has been subscribed by you or any other prior owners if you bought is used.
TiVo Roamio Pro
TiVo Roamio Plus (3tb)
TiVo Mini (three)