It depends on the company. Some include the Annual Management Charge (AMC) in the unit pricing which makes it hard to check as they set the unit price.
Others make an explicit deduction from your policy, which is easier to check. The number of units you hold should be decreasing to pay for the AMC.
If the AMC on your policy is less than the AMC for the fund in general, you will receive bonus units every so often. New Ireland / Bank of Ireland Smart Funds policies spring to mind here. (I've had great fun tracking units on some of them!)
If you want to check values for yourself, you can.
(1) Ask the company for their exact methodology of charging the AMC. (How frequently do they charge? Is it included in the unit price or paid by cancellation of units? Do bonus units apply? How often?) From experience, you may find difficulty locating a member of staff who actually knows this or even has the faintest clue what you're talking about. Try one of the company's actuarial team.
(2) Find out how many units you have.
(3) Find out the current price of one unit.
(4) Model the whole thing on a spreadsheet and track it for a few months.